Patient interface with venting

ABSTRACT

Interfaces for positive pressure therapy having various vent designs are disclosed herein. The interfaces include a bias flow vent with design geometries that help reduce and/or minimize draft and noise levels of the fluids exiting the vents. Some of the vent designs include particular vent hole geometries, plenum spaces, diffusers and fibrous media.

INCORPORATION BY REFERENCE TO ANY PRIORITY APPLICATIONS

Any and all applications for which a foreign or domestic priority claimis identified in the Application Data Sheet as filed with the presentapplication are hereby incorporated by reference and made a part of thepresent disclosure.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to patient interfaces forrespiratory therapy. More particularly, certain aspects of the presentdisclosure relate to various systems and methods for venting gases frompatient interfaces.

2. Description of the Related Art

The treatment of obstructive sleep apnea (OSA) by continuous positiveairway pressure (CPAP) flow generator systems involves the continuousdelivery of pressurized gases to the airways of a human via a conduitand an interface (e.g., a mask). Typically the interface creates atleast a substantial seal on or around the nose and/or the mouth. As thepatient breathes, carbon dioxide gases can progressively accumulate inthe delivery system, which if left over a period of time, can becomehazardous to the patient.

One solution to this issue is to provide washout vents, also known asbias flow vents, which enable a flow of gases to be exhausted to theatmosphere and provides a mechanism for reducing or removing theaccumulation of carbon dioxide gases.

The vents, while providing a mechanism for removing carbon dioxide, alsohave trade-offs. The vents can create a disturbance for the patientand/or the patient's bed partner. This disturbance typically manifestsitself in two forms: noise and the creation of a draft.

SUMMARY OF THE DISCLOSURE

The creation of practical and not-so-practical solutions to thedrawbacks of washout vents has been the subject of considerabledevelopment effort from numerous organisations which has resulted innumerous patents. However, a need still exists for improved designs.

It is an object of the present disclosure to provide one or moreconstructions and/or methods that will at least go some way towardsimproving on the above or that will at least provide the public or themedical profession with a useful choice. The following is a descriptionof a number of practical options to improve current designs.

In accordance with at least one of the embodiments disclosed herein, apatient interface is provided comprising a body portion sized and shapedto surround the nose and/or mouth of a user and adapted to create atleast a substantial seal with the user's face, a coupling that permitsthe patient interface to be coupled to a gas delivery system, and a ventthat allows the passage of gas from an interior of the body portion toan exterior of the body portion, the vent comprising a plurality of exitholes arranged in an array.

A diameter of each of the plurality of exit holes can be between about0.5 mm and about 1.5 mm. A length to diameter ratio of each of theplurality of exit holes can be at least about 2. A ratio of a pitchdistance between each of the plurality of exit holes to the diameter canbe at least about 4. An exit radius of each of the plurality of exitholes can be at least about 0.5 mm. An entry radius of each of theplurality of exit holes can be at least about 0.5 mm.

In some configurations, the gas that exits the vent enters directly intoa plenum chamber defined by the patient interface. The plenum chambercan be defined between the body portion and a frame portion or a shroudof the patient interface. The plenum space can also contain a fibrousmedia.

In some configurations, the vent is located on the coupling and theplenum chamber is defined between the coupling and a shroud that atleast partially surrounds the coupling. The coupling can be aball-jointed elbow or a swiveling joint.

In some configurations, the gas that exits the vent enters a diffuser.The diffuser can be frustoconical in shape. The diffuser can have anexpansion angle of at least about 4 degrees and/or less than or equal toabout 8 degrees. The length to root diameter ratio of the diffuser canbe at least about 1.5 to 1.

In accordance with at least one of the embodiments disclosed herein, apatient interface is provided comprising a body portion sized and shapedto surround the nose and/or mouth of a user and adapted to create atleast a substantial seal with the user's face, a coupling that permitsthe patient interface to be coupled to a gas delivery system, a ventthat allows the passage of gas from an interior of the body portion toan exterior of the body portion, the vent comprising a plurality of exitholes arranged in an array, and a plenum chamber that receives the gasexiting the vent.

In some configurations, the plenum chamber is configured to return theexit gas flow back on itself. The plenum chamber can have a cone angleof between about 4 degrees and about 8 degrees. The plenum chamber canhave a length to root diameter ratio of at least about 1.5 to 1.

In some configurations, the plenum chamber is defined between the bodyportion and a frame portion or a shroud of the patient interface. Theframe portion or the shroud can be positioned between about 3 to about 5hole diameters from the vent. The frame portion or the shroud can definea textured surface facing the vent.

In some configurations, the vent is located on the coupling and theplenum chamber is defined between the coupling and a shroud that atleast partially surrounds the coupling. The coupling can be aball-jointed elbow. The shroud can be positioned between about 3 toabout 5 hole diameters from the vent. The shroud can define a texturedsurface facing the vent.

In some configurations, the plenum chamber re-directs the gas flowthrough an angle of between 45 degrees and about 135 degrees. The plenumchamber at the exit point of the gas flow to ambient can form a sharpcorner between the inner surface and the adjoining surface. The plenumchamber at the exit point of the gas flow to ambient can have a radiusapplied to the corner between the inner surface and the adjoiningsurface.

In some configurations, the plenum chamber is defined as the spacebetween the body portion or cap and a frame portion of the patientinterface. The plenum chamber can be in the shape of an annulus.

In some configurations, the plenum space also contains a fibrous media.All of the vented gas exiting the plenum space into the ambient spacecan pass through the fibrous media.

In accordance with at least one of the embodiments disclosed herein, apatient interface is provided comprising a body portion sized and shapedto surround the nose and/or mouth of a user and adapted to create atleast a substantial seal with the user's face, a coupling that permitsthe patient interface to be coupled to a gas delivery system, a ventthat allows the passage of gas from an interior of the body portion toan exterior of the body portion, the vent comprising a plurality of exitholes arranged in an array, and a textured/fibrous surface defined by acomponent of the patient interface located in front of and facing thevent.

In some configurations, the component is a shroud or a frame portion oran extra component. The textured surface can be located between about 3hole diameters and about 5 hole diameters from the vent.

In accordance with at least one of the embodiments disclosed herein, apatient interface is provided comprising a body portion sized and shapedto surround the nose and/or mouth of a user and adapted to create atleast a substantial seal with the user's face, a coupling that permitsthe patient interface to be coupled to a gas delivery system, whereinthe coupling comprises a rotational joint, and a vent that allows thepassage of gas from an interior of the body portion to an exterior ofthe body portion, wherein the vent comprises a plurality of passagesincorporated in the rotational joint of the coupling.

In some configurations, the rotational joint can be a swivel joint. Inother configurations, the rotational joint can be a ball joint.

In some configurations, the plurality of passages can be formed in thefemale portion of the coupling. The plurality of passages that areformed in the female portion of the coupling can be combined with agutter or leak channel.

In other configurations, the plurality of passages can be formed on themale portion of the coupling. The plurality of passages that are formedon the male portion of the coupling can extend sufficiently to preventocclusion when the coupling is positioned at the extremes of motion.

BRIEF DESCRIPTION OF THE DRAWINGS

Specific embodiments and modifications thereof will become apparent tothose skilled in the art from the detailed description herein havingreference to the figures that follow, of which:

FIG. 1 is a perspective view of a respiratory interface on a patient'shead.

FIG. 2 shows an example of a fluid flow through a vent hole.

FIG. 3 is a cross-sectional view of vent holes according to anembodiment of the present disclosure.

FIG. 4 shows a graphical representation of a design envelope for exitradius versus hole diameter for vent holes.

FIG. 5 is a graph showing sound pressure versus exit radii for a 1 mmvent hole.

FIG. 6 shows a graphical representation of a design envelope for holelength/diameter ratio versus hole pitch/diameter ratio for vent holes.

FIG. 7 is a graph showing sound pressure versus length/diameter ratiofor a 1 mm vent hole having a 0.5 mm exit radius.

FIG. 8 is a graph showing sound pressure versus hole pitch for a 1 mmvent hole having a 0.5 mm exit radius.

FIG. 9 is a cross-sectional view of a respiratory interface according toan embodiment of the present disclosure.

FIG. 10 is a cross-sectional view of a respiratory interface accordingto another embodiment of the present disclosure.

FIG. 11 is a cross-sectional view of a diffuser according to anembodiment of the present disclosure.

FIG. 12 is a cross-sectional view of a vent having fibrous media,according to an embodiment of the present disclosure.

FIG. 13 is a perspective view of a respiratory interface according toanother embodiment of the present disclosure.

FIG. 14 is a cross-sectional view of an annulus cap according to anembodiment of the present disclosure.

FIG. 15 is a cross-sectional view of an annulus cap with fibrous mediaaccording to an embodiment of the present disclosure.

FIG. 16 is a side view of a respiratory interface according to anotherembodiment of the present disclosure.

FIG. 17 is a cross-sectional view of a ball socket with groovesaccording to an embodiment of the present disclosure.

FIG. 18 is a side view of a connection port assembly with a ball endhaving grooves according to an embodiment of the present disclosure.

FIG. 19 is a cross-sectional view of a ball joint according to anembodiment of the present disclosure.

FIG. 20 is a cross-sectional view of a ball joint according to anotherembodiment of the present disclosure.

FIGS. 21A-L are perspective views of ball socket components with groovepatterns, according to various embodiments of the present disclosure.

FIG. 22A is a front perspective view of a ball socket component with aplenum space, according to an embodiment of the present disclosure.

FIG. 22B is a back perspective view of the ball socket component of FIG.22A.

FIG. 22C is a cross-sectional view of the ball socket component of FIG.22A.

FIG. 23 is a perspective view of a vent module, according to anembodiment of the present disclosure.

FIG. 24 is a perspective view of an interface with the vent module ofFIG. 23.

FIG. 25 is a perspective view of a mask frame, according to anembodiment of the present disclosure.

FIG. 26 is a perspective view of the interface of FIG. 24 and the maskframe of FIG. 25.

FIG. 27 is a perspective view of a connection port assembly having avent, according to an embodiment of the present disclosure.

FIG. 28 is a close-up perspective view of the vent of FIG. 27.

FIG. 29 is a perspective view of the connection port assembly of FIG. 27without the vent cover.

FIG. 30 is a perspective view of the vent cover of FIG. 27.

FIG. 31A is a perspective view of a vent module, according to anembodiment of the present disclosure.

FIG. 31B is a perspective view of the vent module of FIG. 31A, in acurved configuration.

FIG. 31C is a perspective view of the vent module of FIG. 31A attachedto a connection port assembly.

FIG. 32A-E are perspective view of bendable vent modules, according tovarious embodiments of the present disclosure.

FIG. 33A is an exploded view of an interface with slots, according to anembodiment of the present disclosure.

FIG. 33B is a cross-sectional view of the interface of FIG. 33A.

FIG. 34A is an exploded view of an interface with slots, according toanother embodiment of the present disclosure.

FIG. 34B is a cross-sectional view of the interface of FIG. 34A.

FIG. 35A is a perspective view of a connection port assembly with slots,according to an embodiment of the present disclosure.

FIG. 35B is a cross-sectional view of the connection port assembly ofFIG. 35A.

FIGS. 36A-F are cross-sectional view of various embodiments of slots.

DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS

With reference initially to FIG. 1, an embodiment of an interface 100 isillustrated on a user U. The interface 100 can be used in the field ofrespiratory therapy. In some embodiments, the interface 100 hasparticular utility with forms of positive pressure respiratory therapy.For example, the interface 100 can be used for administering continuouspositive airway pressure (“CPAP”) treatments, variable positive airwaypressure (“VPAP”) treatments and/or bi-level positive airway pressure(“BiPAP”) treatments. The interface can be compatible with one or moredifferent types of suitable CPAP systems.

The interface 100 can comprise any of a plurality of different types ofsuitable mask configurations. For example, certain features, aspects andadvantages of the present invention can be utilized with nasal masks,full face masks, oronasal masks or any other positive pressure mask.Although the illustrated mask is a full face mask, the scope of thepresent disclosure should not be limited by the particular embodimentsdescribed.

In the illustrated configuration, the interface 100 comprises a maskbody 102, a mask frame 104 and a connection port assembly 106. The maskbody 102 is configured to cover the user's mouth and/or nose to deliverrespiratory gases to the user. The mask body 102 can be secured to themask frame 104. The mask frame 104 is held in place by a headgearassembly that wraps around the user's head. A connection port assembly106 can be connected to the mask body 102 and/or mask frame 104,preferably with a releasable connection. In some configurations, theconnection port assembly 106 can include a ball joint to improveflexibility and comfort.

The mask frame 104 can couple to the mask body 102 and help stabilizethe interface 100 on the user's face. The mask frame 104 can be anyshape and size to functionally secure the interface 100 to the user'sface. The mask frame 104 can be attached to the mask body 102 withinterlocking clips, tabs or other functional couplers. The mask frame104 can be rigid, substantially rigid or semi-rigid to provide supportfor the mask body 102. For example, the mask frame 104 can be at leastpartially made of a metal or rigid plastic, such as acrylic,polycarbonate or high-density polyethylene.

As illustrated in FIG. 1 the mask frame 104 can extend to the user'sforehead and include a forehead rest 108. The forehead rest 108 can helpstabilize the interface 100 to the user's face by providing a supportpoint for the interface 100 and connection points for the headgearassembly. In the illustrated configuration, a frame bridge 110 extendsfrom the main body of the frame and is connected to the forehead rest108. The frame bridge 110 can be integrally formed or molded with therest of the mask frame 104 from the same rigid material.

In some configurations, the forehead rest 108 can be a separate flexiblepiece that is attached or overmoulded onto the mask frame 104. Forexample, the forehead rest 108 can be made of a flexible silicone thatis overmoulded onto the frame bridge 110. The flexible materialadvantageously conforms to the user's forehead anatomy and helps improvecomfort to the user with soft material contact. In some configurations,the forehead rest 108 can be attached or integrally formed as part ofthe mask frame 104 and can be made of the same material as the maskframe 104 and frame bridge 110.

The typical method of passively venting carbon dioxide (CO2) is via theuse of a hole or a hole array that is incorporated into the mask body orgas path componentry that, for example, is directly connected to themask. In the embodiment illustrated in FIG. 1, the interface 100 hasvents 112 for expelling gases from inside the mask to the environment.The vents 112 can help expel carbon dioxide gases from the user toreduce the rebreathing of the carbon dioxide gases.

The vents 112 create a controlled or known leak to enable the exhaustingof the user's exhaled carbon dioxide gases. There may be a performancetrade-off between the location of the vents (relative to the patient'smouth or nose) and the amount of bias flow required. As used herein,bias flow refers to the flow of gases to the environment through thevents. The flow rate of the bias flow and the design geometry of thevent holes can have an effect on the noise level and draft that the biasflow produces, as well as the amount of entrainment that the exiting gasflow may cause, as discussed further below.

In the illustrated configuration, the vents 112 comprise a plurality ofthrough holes on the mask body 102 that expel gases through a cutout 116in the mask frame 104. In other configurations, the vents can be slitsor large openings instead of or in addition to small through holes. Insome configurations, the vents can be disposed on other portions of theinterface, such as the connection port assembly or connection joints, asdiscussed below. Generally, relatively smaller hole sizes produce lessairflow noises compared to a larger hole size given the same flowvelocity through both hole sizes. The plurality of holes helps reduceairflow noises compared to having one or a few holes with the same ventarea when expelling a given volume of gas.

In some embodiments, the vents 112 can be formed as a separate componentfrom the mask body or mask frame. The separate vent module can bepermanently or releasably assembled to the mask body or mask frame. Forexample, the vent module can have threads that mate with complementarythreads on the mask body. In other configurations, the air vent modulecan have any type of functional coupler to mate the vent module to themask body or mask frame. In these configurations, the vent module can beremoved easily for service, cleaning or replacement.

The vent module can be overmoulded to the mask body or mask frame for apermanent attachment. The overmoulding can include a flexible gussetbetween the vent module and the mask that helps with flexibility. Inother configurations, the vent module can be permanently attached using,for example, adhesives or ultrasonic welding.

Furthermore, the vents 112 can be formed of a different material thanthe mask body or mask frame. This can advantageously allow the vents tobe made of a material that is suitable for forming apertures. Forexample, the vents can be made of a soft and/or flexible material whilethe mask body and/or mask frame are made of a more rigid material. Insome configurations, the soft and/or flexible material (e.g., silicone,rubber, foam and the like) may help reduce the amount of noise the flowmakes through the apertures. However, in some embodiments, the vents 112can be formed of the same material as the mask body and/or mask framewhile providing acceptable noise and draft levels.

A separate vent module advantageously allows improved manufacturing andproduct quality. By having the vents in a separate component themoulding of the small and detailed vent apertures can be bettercontrolled. By moulding the vents as a separate component, the parttolerances can be better controlled and result in more consistent holedimensions having a more consistent flow rate performance between parts.Moulding a separate vent module may allow for production of more complexvent designs as a result of not having to accommodate undercuts andother geometric restrictions of other components, such as the mask bodyfor example. Improved control of the part dimensions may also improvecontrol of noise levels, such as by controlling the part contours toproduce a smooth air flow through the holes.

It has been learned that optimizing the design of the vent hole geometryand the adjoining plenum chamber can be beneficial in reducing the noiseand draft levels of the fluids exiting the vents. Various definitionscan be used to quantify or measure sound levels.

First, sound power can be used to quantify the sound levels. This is themeasure of the amount of energy from a particular sound source. Themeasurement is independent of distance from the sound source. Second,sound pressure can be used to quantify sound levels. This is the measureof the intensity of the sound at a particular distance from the soundsource. This is typically measured in decibels (i.e., dB or dBa). Athird method of quantifying sound levels is a sound field. A sound fieldis a graphical representation (i.e., a contour map) of the pressurelevels of a particular sound as a function of position from the soundsource.

FIG. 2 illustrates an example of a fluid flow passing through a venthole 114. As used herein, the term fluid is used to refer to liquids,gases or a combination of liquids and gases. During the process offlowing through the vent hole 114 a complex set of fluid dynamicsoccurs, for which there is considerable digital and experimental baseddata sets to describe its behaviour.

When a fluid flow experiences a sudden contraction in the flow path,such as with vent holes, the flow contracts through a minimumcross-section called the vena contracta 120, as illustrated in FIG. 2.The position of the vena contracta 120 is downstream of the vent hole114 entrance. Substantially all the fluids that passes through the venthole 114 will pass through the vena contracta 120 and this location isalso the location of highest flow velocity and lowest pressure.

As the fluid flow exits the vena contracta 120, it progressively reducesin velocity and increases in pressure, until it reaches a velocity ofapproximately zero and a pressure of approximately atmospheric pressure.In this transition zone after the vena contracta 120, vortices 122 mayform at the boundary between the exiting fluid flow and the stationaryatmospheric air, which are caused by viscous effects between the twofluids being at different velocities. This effect is known as vortexshedding. At a macro level, the vortex shedding may produce rapid randomfluctuations which occur across a range of frequencies. Typically, thefrequencies can range from at least approximately 1 kHz to less than orequal to 10 kHz, with wavelengths in the range of at least approximately1 mm to less than or equal to 4000 mm.

There are a number of geometric factors that influence the amount ofsound energy created by the vortex shedding. These geometric variablescan be utilised during the design of the vent holes 114 to reduce andminimise the amount of sound energy created when fluids travel throughthe vents 112. With reference to FIG. 3, the variables can include: (1)The flow rate through the vent hole 114, which is a function of the holediameter 130 and the pressure drop from the entrance to the exit of thevent hole; (2) The quality of the vent hole, which can be characterisedby the smoothness of the hole and the absence of debris in the hole; (3)The geometry of the hole, particularly the entrance radius 132 and exitradius 134 of the hole, and the hole length 136 to diameter 130 ratio ofthe hole; (4) The geometry of the hole array, for example the hole pitch138 (i.e., the distance between vent holes).

The two most commonly understood flow types are laminar flow andturbulent flow, which can be quantified by a Reynolds number. For designpurposes, the Reynolds number at which the transition between laminarflow and turbulent flow occurs is approximately 2300. In situationswhere turbulent flow occurs at the vena contracta, there is usually anincrease in sound level. Furthermore, when debris or surfaceimperfections exist in the vent holes, this can create a mechanism thatpromotes an earlier transition from laminar flow to turbulent flowcompared to smooth surface vent holes.

Being able to adjust the geometry of the vents offers the ability tocontrol the sound levels produced by the vents to be within anacceptable range for use as part of a CPAP system. Some design envelopeshave been developed that achieve acceptable sound levels. One of thedesign envelopes is for the vent hole diameter 130 versus the exitradius 134. A graphical representation of the design envelope showingvent hole diameter versus the exit radius is illustrated in FIG. 4.

The contour of the exit radius 134 can affect the noise levels that arecreated by the fluid flow. In some configurations, the exit radius 134can be at least approximately 0.25 mm and/or less than or equal toapproximately 0.75 mm. As discussed below, this range is preferable forreducing or minimizing the noise levels created by a 1 mm vent hole.Similarly, the contour of the entrance radius can affect the noiselevels that are created by the fluid flow. In some configurations, theentrance radius can be at least approximately 0.25 mm. In someconfigurations, the entrance radius can be at least approximately 0.1 mmand/or less than or equal to approximately 1 mm.

FIG. 5 illustrates a graph illustrating sound pressure versus exitradius for a 1 mm vent hole. As shown in the graph, sound levels arerelatively high when the exit radius is zero. The sound levels steadilydecrease to a minimum sound level at approximately 0.5 mm exit radius.The sound levels slowly increase as the exit radius is increased. Arange of approximately 0.25 mm and/or less than or equal toapproximately 0.75 mm has been found to be a range that providesacceptable noise levels.

The contour of the exit radius 134 can also substantially reduce thevariation in the noise level that is created as the flow rate ischanged. The noise level can have minimal variation as the drivingpressure from the CPAP unit changes. Accordingly, the vent can have asubstantially constant sound output that is predictable throughout arange of driving pressures. The entrance radius 132 has similar effectson the sound power level, although a less pronounced effect compared tothe exit radius 134.

In some configurations, the hole diameter 130 can be at leastapproximately 0.5 mm and/or less than or equal to approximately 1.5 mm.Producing vent hole diameters smaller than 0.5 mm can be difficult orimpractical using conventional injection molding techniques. With venthole diameters larger than 1.5 mm, the sound power created by the gasflow can produce sound pressure levels larger than what is acceptablefor some applications.

Although FIG. 4 illustrates a preferable design envelope to achievedesirable sound levels produced by the vents, in some configurations theranges for vent hole diameter and exit radius can be broader while stillachieving acceptable sound levels. For example, in some configurations,the exit radius can be at least approximately 0.1 mm and/or less than orequal to approximately 1 mm. Furthermore, in some configurations, thehole diameter can be at least approximately 0.25 mm and/or less than orequal to approximately 2 mm.

Another design envelope is for hole pitch/diameter ratio versus the holelength/diameter ratio. A graphical representation of the design envelopeshowing hole pitch/diameter ratio versus the hole length/diameter ratiois illustrated in FIG. 6.

In some configurations, the vent hole length to diameter ratio can be atleast approximately 2. Having a hole length to diameter ratio below 2may significant increase the sound power level for a given hole size.For example, a hole length to diameter ratio of 1.5 can approximatelydoubles the decibel sound output compared to a ratio of 2. However, insome configurations, the vent hole length to diameter ratio can be atleast approximately 1 while still providing acceptable sound levels.

FIG. 7 is a graph showing sound pressure versus length/diameter ratiofor a 1 mm vent hole having a 0.5 mm exit radius. As shown in the graph,sound levels are relatively low at a length/diameter ratio ofapproximately 1. The sound levels rapidly increase to a maximum soundlevel at a ratio of approximately 1.5. The sound levels rapidly decreaseto a minimum at a ratio of approximately 2. The sound levels slowlyincrease as the ratio increases above 2. Accordingly, a range for thelength/diameter ratio of greater than approximately 2 has been found tobe an acceptable range for minimizing noise levels.

Once the design has been established for a single hole and the resultingflow rate for that hole is established, the number of holes required forsufficient carbon dioxide flushing can be determined. Multiple ventholes can be positioned in a vent hole array. In some configurations,the vent hole pitch (i.e., the distance between holes) to diameter ratiocan be at least approximately 4. Generally, for ratios outside thisdesign envelope, the fluid flows from the individual holes can have astrong interaction with each other, which multiplies the sound output.However, in some configurations, the vent hole pitch to diameter ratiocan be at least approximately 3.

FIG. 8 is a graph showing sound pressure versus hole pitch for a 1 mmvent hole having a 0.5 mm exit radius. As shown in the graph, soundlevels are relatively high when the hole pitch is approximately 2. Thesound levels decrease to a minimum sound level at a pitch ofapproximately 4. The sound levels slightly increase as the hole pitch isincreased. Accordingly, a range for the hole pitch of at leastapproximately 4 has been found to be an acceptable range for minimizingnoise levels.

The fluid flow exiting the vent holes are at a relatively high velocity,typically 20-50 m/sec. Due to conservation of energy and momentum, theexiting fluid flow entrains the surrounding environmental air. The fluidflow is at a lower pressure than the surrounding air and the pressuredifferential causes a portion of the surrounding environmental air to beentrained and moved along with fluid flow, which multiplies many timesthe effective draft from the vent holes. The experimentally determinedincrease of the effective draft may be in the order of 6-10 times. Forexample, a vent hole array with a 10 cm H2O change in pressure from theentrance to exit will create a bias flow of approximately 15-20liters/min. The effect of the entrainment can result in approximately90-120 liters/min of total flow being projected towards the user or bedpartner. Accordingly, the ability to control the rate of entrainment candirectly affect the ability to minimize the disturbance caused by theeffective draft.

In some configurations, the draft and noise from the vents can bereduced or minimized by using a plenum chamber that enables the energypresent in the exiting fluid flow to dissipate. The plenum chamber canenable the fluid velocity to slow and the fluid pressure to increase toreduce or prevent entrainment. The plenum chamber can have any of aplurality of different types of shapes or designs. In someconfigurations, the plenum chamber can be an expansion chamber thatsubstantially reduces or prevents environmental air from beingentrained, as illustrated in FIGS. 9 and 10.

FIG. 9 illustrates a cross-section view through an interface 200 withvent holes 214 disposed in a forward-facing surface of the mask body 202that is above the connection port assembly 206. The mask frame 204 ispositioned in front of the mask body 202, such that the venting fluidflow passes through the vent holes 214 and into a plenum space 240created between the mask body 202 and the mask frame 204. The plenumspace 240 causes the fluid flow to change direction, which reduces thevelocity and increases the pressure of the fluid flow. After the energyin the fluid flow is reduced, the vented fluids can exit the plenumspace 240 into the environment with minimized or reduced noise levels.

FIG. 10 illustrates a cross-sectional view of an embodiment of aninterface 300 having vent holes 314 on the connection port assembly 306,disposed between the mask body 302 and the connection end 318 for thegas delivery circuit. The vent holes 314 are disposed around the entirecircumference of the connection port assembly 306 in the illustratedconfiguration. In other configurations, the vent holes may be disposedon only a portion of the circumference, such as the front side or onlyhalf of the circumference of the connection port assembly 306. Theconnection port assembly 306 can have an outer shell 342 that surroundsthe vent holes 314. In the illustrated embodiment, the outer shell 342extends to cover approximately the upper half of the connection portassembly 306. In other embodiments, the outer shell can cover more orless of the connection port assembly than illustrated, but preferablycovers the vent holes.

The space between the outer shell 314 and the inner surface of theconnection port assembly 306 is the plenum space 340. The venting fluidpasses through the vent holes 314 and into the plenum space 340, whichin some configurations is designed to turn the fluid flow back onitself. The plenum space 340 reduces the velocity and increases thepressure of the fluid flow. After the energy in the fluid flow isreduced, the vented fluids can exit the plenum space 340 into thesurrounding environment with minimized or reduced noise levels.

In some configurations, the draft and noise levels from the vents can bereduced or minimized by the application of a steadily increasingcross-sectional area, such as a diffuser 460 as illustrated in FIG. 11.FIG. 11 illustrates a cross-section of a diffuser 460 that is effectiveat reducing the fluid flow velocity, which reduces the draft and noiselevels. The smaller end of the diffuser 460 surrounds the vents 412 andthe wider end of the diffuser 460 can be open to the environment. Thediffuser can have a conical shape, or other shape that has an increasingcross-sectional area. Some examples include a pyramid-shaped cone, atriangular cone and a polygonal cone.

Some geometric design considerations that can help to reduce the fluidflow velocity include the expansion angle α and the ratio of thediffuser length 462 to the root diameter 464. Diffusers with geometriessimilar to those described below have resulted in a reduction of thefluid flow velocity from approximately 6-8 meters per second to lessthan 0.8 meters per second in some embodiments.

The diffuser 460 can have an expansion angle α of at least approximately4 degrees and/or less than or equal to approximately 8 degrees, orgeometry that has the same effective cross sectional area behaviour. Ithas been discovered that angles greater than about 8 degrees aregenerally not very effective at reducing draft and noise levels in someapplications. However, in some configurations, the diffuser can have anexpansion angle α of at least approximately 1 degrees and/or less thanor equal to approximately 15 degrees.

The length of the diffuser should be long enough to provide sufficientdistance for the fluid flow velocity to decrease to a desirable level,while not protruding too much from the mask to where it causes anobstruction. For larger vents, the diffuser length can beproportionately larger to achieve the desired reduction in draft andnoise levels. The ratio of the diffuser length 462 to the root diameter464 can be at least approximately 1.4:1. In some embodiments, the ratioof the diffuser length 462 to the root diameter 464 can be at leastapproximately 1.25:1 and/or less than or equal to approximately 1.9:1.

With reference to FIG. 12, in some configurations, a textured or fibrousmedia 166 is positioned in front of the vent holes 114 such that thefluid flow exiting the vent holes impinges on the media 166. Someexamples of textured or fibrous media can include wool, cotton, felt,polyester, open cell foam and the like. The media 166 helps to reducethe fluid flow velocity and diffuse the fluid flow, which reduces thedraft and noise levels. The media 166 is preferably positioned betweenthe exit of the vent holes 114 and a distance from the vent holes 114 atwhich the exiting fluid flow produces sound. In some configurations, themedia distance β can be at least approximately 3 times the vent holediameter and/or less than or equal to approximately 5 times the venthole diameter. In some configurations, the media distance β can be atleast approximately 1 time the vent hole diameter and/or less than orequal to approximately 10 times the vent hole diameter.

Another advantage of positioning the media 166 a distance β from thevent hole exits is that it can prevent accumulation of water around thevent holes caused from condensation of the fluid flow. The condensationcan occlude the vent hole exits and undesirably increase the resistanceto flow (i.e., drop in bias or leak flow rate).

Another vent design can include the use of an annulus configurationwhere the fluid flow exits through a hole or hole array and is thenexhausted radially outward by an annulus cap that redirects the fluidflow through a plenum space and eventually vents to environment. In someconfigurations, the plenum chamber can redirect the gas flow through anangle of between 45 degrees and about 135 degrees. FIG. 13 illustratesan embodiment of an interface 500 with an annulus cap 570 that vents thefluid flow radially outward, reducing the fluid flow velocity, the draftand noise levels. In the illustrated embodiment, the annulus cap 570 islocated on the mask frame 504 above the connection port assembly 506. Insome embodiments, the annulus cap can be disposed on the mask body 502or the connection port assembly 506 instead of or in addition to themask frame 504.

FIG. 14 illustrates a cross-section of an annulus cap 570 showing thefluid flow through the cap. The annulus cap 570 covers vent holes 514that are in fluid communication with the inside of the mask body. Thefluids can flow through the vent holes 514 and are directed through aplenum space 540. The direction of the fluid flow is also redirected toexhaust radially outward. As described previously, the fluids flowthrough the vent holes 514 at a relative high velocity and low pressure.As the fluids enter the plenum space 540, they are redirected by thewalls of the annulus cap 570, which reduces the fluid flow velocity andincreases the fluid pressure. The fluids flow through the plenum space540 and exit to the environment in a radial direction. The annulus cap570 reduces or minimises the sound creation from the fluid flow.

In the illustrated configuration, the annulus cap 570 is integrallyformed with one of the interface components, such as the mask body, maskframe or connection port assembly. In some configurations, the annuluscap can be a separate component that is fastened over the top of thevents with a functional coupler, such as threaded fasteners, clips or aninterference fit.

There are a number of geometric factors that influence the amount ofsound energy created by the vortex shedding as the fluid flow exits theannulus cap. These factors can include: (1) the cross-sectional area ofthe plenum space 540, which affects the fluid velocity exiting the slot;(2) the profile of the plenum space 540, which also affects the fluidvelocity exiting the slot; and (3) the exit radii 572 of the annulus cap570 surrounding the plenum space exit, which influences the location andresulting sound level of the vortex shedding that occurs in the existingfluid flow. Similar to as discussed above, a given flow volume will havea greater velocity through a relatively smaller cross-sectional areacompared to a relatively larger cross-sectional area. Higher flowvelocities can produce more draft and sound levels.

The profile of the plenum space 540 can be configured to slow down thefluid velocity and help reduce noise levels. For example, in theconfigurations illustrated in FIGS. 14 and 15, the plenum space 540includes pockets 544 adjacent the outlet side of the vent hole 514. Whenthe fluid flow enters the pocket 544, it can create turbulence that slowdown the fluid flow, which can help reduce noise levels of the fluidflow exiting the annulus cap.

Similar to as discussed above, the fluid flow exiting the annulus cap570 are at a relatively high velocity. Due to conservation of energy andmomentum, the exiting fluid flow entrains the surrounding environmentalair. The fluid flow is at a lower pressure than the surrounding air andthe pressure differential causes a portion of the surroundingenvironmental air to be entrained and moved along with fluid flow, whichmultiplies many times the effective draft from the vent holes. Theability to control the rate of entrainment can directly affect theability to minimize the disturbance caused by the effective draft.

In some configurations, the rate of entrainment can be reduced by theuse of a fibrous media 566 positioned in the flow path, as illustratedin FIG. 15. In the illustrated configuration, the fibrous media 566 istoward the exit of the plenum space 540. In other configurations, thefibrous media 566 can be positioned anywhere along the flow path throughthe annulus cap 570. The fibrous media 566 can provide a tortuous pathfor the fluid flow to pass through, which produces friction and reducesthe fluid velocity. The fluid velocity can be reduced to a level ofsufficiently low energy that the velocity difference between the fluidflow exiting the annulus cap 570 and the surrounding air is at a pointthat there is minimal or reduced entrainment of the surrounding air.

Instead of or in addition to having vents on the mask body or maskframe, the bias flow can be incorporated into the leak rate thatnormally occurs through a ball joint or swiveling joints present in someinterfaces. Some interfaces have either a ball joint or a swivel jointto help reduce or minimize the effect of torque that the delivery tubemay induce on the interface and user. These joints provide free motionwith low or minimal leak rate. The descriptions below relate to aninterface having a ball joint. However, it should be understood that thesame design concepts can be applied to swivel joints.

In some configurations, the connection port assembly 206 can beconnected to the mask body 202 with a ball joint 250, as illustrated inFIG. 9. In some configurations, the connection port assembly 206 can beconnected to the mask frame 204 instead of or in addition to the maskbody 202. In the illustrated configuration, the mask body 202 has a ballsocket 252 with a concave surface configuration that can receive a ballend 254 of a connection port assembly 206. The ball end 254 has an outersurface that is contoured to be snap fit into the ball socket 252. Theball joint 250 can allow the surfaces to slide relatively freely witheach other such that the angle between the connection port assembly 206and mask body 202 can be easily changed.

There are several options for the geometry of the gas path through aball joint or swivel joint that can produce a stable, predictable leak.With reference to FIG. 16, an interface 600 is shown having a ball joint650 between the connection port assembly 606 and mask body 602. The balljoint 650 includes grooves 656 that allow the fluids in the mask toexhaust to the environment in a controlled, predictable manner. Thequantity and cross-sectional area of the grooves 656 can affect the flowrate of fluids venting through the ball joint.

The grooves can be disposed on either or both components of the balljoint. For the example, FIG. 17 illustrates grooves 756 on the interiorsurface of the ball socket 752. The ball socket 752 can be a part of themask body 702, as illustrated, or the mask frame. In someconfigurations, the grooves 856 can be disposed on the exterior surfaceof the ball end 854 of the connection port assembly 806, as illustratedin FIG. 18. The grooves provide fluid communication between the insideof the mask to the environment while also providing a mechanism toreduce the friction between the ball and the socket. The reducedfriction is advantageous for further reducing the effect of tube torqueon the interface.

Preferably, the ball joint can provide a consistent, reliable leak rateindependent of the orientation of the ball socket. The cross-sectionalareas of each groove can be substantially the same so that the leak rateis the substantially the same no matter which orientation the ballsocket is in.

In addition, the ball joint can be designed to minimize the obstructionof the air pathway as the fluids exit the joint. If there areobstructions in the fluid pathway, the sound levels may change as theball joint is moved, especially when flexed to its extremes. Forexample, FIG. 19 illustrates a ball joint 950 with a ball socket 952 andball end 952. The grooves 956 are disposed on the outer surface of theball end 952 and extend to or beyond the neck 957 of the ball end.Because the grooves 956 extend to or beyond the neck 957, the socketedge 958 does not occlude the flow path of the exhaust fluid when theball joint is flexed to its extremes, which can lead to unstable flowrates and noise level changes.

FIG. 20 illustrates a configuration of a ball joint 1050 having a gutter1059 on the socket edge 1058. The ball joint 1050 has a ball socket 1052and ball end 1054, with grooves 1056 disposed on the ball end 1054.Instead of the grooves 1056 extending to the neck of the ball end tohelp prevent occlusion of the fluid flow, the illustrated gutter 1059provides clearance for a fluid pathway when the ball joint is flexed toits extremes.

In some embodiments, the interface can have a separate ball socketcomponent that can be separately made and coupled to the mask body ormask frame. A separate ball socket component can advantageously allowimproved manufacturing and product quality. The small and detailedfeatures, such as the grooves, can be better controlled and the parttolerances can be better controlled and result in more consistentdimensions having a more consistent flow rate performance. Moulding aseparate ball socket component may also allow for production of morecomplex groove designs as a result of not having to accommodateundercuts and other geometric restrictions of other components. The ballsocket component can be attached to the mask body or mask frame throughany type of functional coupling, such as overmoulding, adhesives, clips,welding and interference fit.

FIGS. 21A-L illustrate some examples of ball socket components with somepossible groove patterns for the ball joint. FIGS. 21A-B illustratefront and rear perspective views, respectively, of a groove pattern.FIGS. 21C-D illustrate front and rear perspective views, respectively,of another groove pattern. FIGS. 21E-F illustrate front and rearperspective views, respectively, of a groove pattern having four largegrooves. FIGS. 21G-F illustrate a front perspective and close-up view ofanother embodiment of a ball socket component with a groove pattern.FIG. 21I-J illustrate a front perspective and close-up view of a groovepattern with a 30 degree twist. FIGS. 21K-L illustrate a frontperspective and close-up view of a groove pattern with an increasednumber of grooves, 75 grooves in the illustrated embodiment.

FIGS. 22A-C illustrate a ball socket component 1151 having a plenumspace 1140. The ball socket component 1151 has a ball socket 1152 foraccepting a ball end. In some configurations, the ball socket can besmooth or have grooves, as discussed above. The rear side of the ballsocket component 1151 can have vent holes 1114 and the front side canhave slots 1115. In some configurations, the front side may haveopenings in other shapes other than slits as shown in the illustratedembodiment. Between the vent holes 1114 and slots 1115 can be a plenumspace 1140 that reduces the fluid flow velocity, and reduces the draftand noise levels.

In some configurations, the vent holes can be disposed on a separateinsert that is coupled to the interface. FIG. 23 illustrates an exampleof a vent module 2112 having a plurality of vent holes 2114. Theseparate vent module 2112 advantageously allows improved manufacturingand product quality. By having the vent holes 2114 in a separatecomponent the moulding of the small and detailed vent apertures can bebetter controlled, and the part tolerances can be better controlled andresult in more consistent hole dimensions having a more consistent flowrate performance. Moulding a separate vent module 2112 may also allowfor production of more complex vent designs as a result of not having toaccommodate undercuts and other geometric restrictions of othercomponents, such as the mask body for example. Improved control of thepart dimensions may also improve control of noise levels, such as bycontrolling the hole contours to produce a smooth air flow through theholes.

FIG. 24 illustrates the vent module 2112 coupled to a mask body 2102.The vent module 2112 can be attached to the mask body 2102 or mask framethrough any type of functional coupling, such as overmoulding,adhesives, clips, welding and interference fit. With reference to FIGS.25 and 26, a mask frame 2104 can be coupled to the mask body 2102. Themask frame 2104 can have a cutout 2116 that is configured to bepositioned over the vent module 2112. In some configurations, a ventcover 2117 can be disposed across the cutout 2116 to reduce the draftfrom the vent holes 2114. The space between the vent module 2112 and thevent cover 2117 can act as a plenum space to reduce the fluid flowvelocity, and reduce the draft and noise levels.

FIGS. 27 and 28 illustrate an embodiment of a connection port assembly3106 having a vent 3112 with a vent cover 3117. The vent 3112 can be asingle opening through the wall of the connection port assembly 3106, asillustrated in FIG. 29, or can be a plurality of holes or slots, asdiscussed previously. FIG. 30 illustrates the vent cover 3117, which canbe a separate component that is coupled to the connection port assembly3106 through any type of functional coupling, such as overmoulding,adhesives, welding, clips and interference fit. In some embodiments, thevent cover is integrally formed or moulded with the connection portassembly.

The vent cover 3117 can help to reduce the draft from the vent 3112. Theplenum space 3140 between the connection port assembly 3106 and the ventcover 3117 can help reduce the fluid flow velocity, and reduce the draftand noise levels as discussed previously.

As mentioned above, having vent holes in a radial configuration, such asaround a cylinder, is beneficial in reducing or minimizing the amount ofdraft that is felt by the user or bed partner. However, moulding radialholes, or holes on a curved surface, can be difficult from a processpoint of view. Accordingly, in some configurations, the vent holes canbe formed on a vent module made of soft material and then attached tothe interface. The soft material can allow for the vent module to bewrapped around or contoured onto the interface. In some configurations,the soft material of the vent module can be rubber, plastic, silicone orany other suitably flexible material. In some embodiments, however, thematerial can be a harder material and can have some functional means ofbeing bent, such as with hinges or reliefs that promote bending.

FIG. 31A illustrates a vent module 3112 that is moulded from a flatpiece of material. As illustrated, the fluid flows in generally the samedirection as it flows out of the vent holes 3114. FIG. 31B illustratesthe vent module 3112 in a curved configuration. The vent holes 3114 arein a radial pattern and the fluid flows from the vent holes 3114 indivergent directions. In other words, when the vent module is curved,there are no two columns of holes at the same angle. This makes itharder for the fluid flow to entrain air and therefore reduces the drafteffect, which can reduce the noise level as well. FIG. 31C illustratesthe vent module 3112 coupled to a connection port assembly 3106. Thevent module 3112 can be overmoulded with the interface or attached byother means, such as for example adhesives or welding.

FIGS. 32A-E illustrate various examples of a vent module that is bentand attached to different portions of interfaces. FIG. 32A illustrates aflat circular vent module 3112 that can be curved into a frustoconicalshape and attached to the interface 3000. In the illustratedconfiguration of FIG. 32B, the vent module 3112 is disposed around theball joint. The vent holes 3114 are pointed in a divergent directionrelative to the centre of the circular vent module 3112, which helpsdiffuse the fluid flow and reduce draft.

FIG. 32C illustrates a horseshoe-shaped vent module 3112 that can fitaround the contours of the connection port assembly. FIG. 32Dillustrates a vent module 3112 that can cover the front portion of themask. In this configuration, the large surface area of the front portioncan be used for vent holes 3114, allowing for a large venting flow rate.FIG. 32E illustrates another embodiment of a vent module 3112 that isconfigured to fit across the front portion of the interface. In theillustrated embodiment, the vent module 3112 includes strips with ventholes 3114 that extend around the ball joint.

It has been discovered that instead of vent holes, slots can be used tovent the fluids. Slots have some advantages over vent holes, which mayinclude more venting flow rate, better manufacturability and lower noiselevels. The slots may produce less noise compared to holes because theslots have less surface structures for the fluid to flow past, which isa contributor to noise production.

FIG. 33A illustrates an exploded view of an interface 4000 having slots4114 for venting. The slots 4114 can be disposed on a vent module 4112and a slot cover 4115 can be positioned over the vent module 4112 toform a flow path through the slots 4114, as illustrated in FIG. 33B. Inthe illustrated embodiment, the slot cover 4115 includes the ball socket4152 such that the connection port assembly 4106 can connect to the slotcover 4115.

With continued reference to FIG. 33A, the vent module 4112 can have aninner radius 4113, which can help provide a smoother flow path throughthe slot and help reduce noise levels. It has been discovered thatplacing a tab 4117 at the exit of the slots 4114 can help to reducenoise levels. In experimentation, an optimal tab 4117 length was foundto be approximately 2 mm long. However, in some embodiments, the tablength can be any length that provides suitable noise reduction. Theillustrated configuration has 4 slots spaced equal distances apart. Insome configurations, the number of slots can be at least 1 and/or lessthan or equal to 8 slots. Furthermore, with reference to FIG. 33B, theexhausting fluid flow is shown flowing radially outward from theinterface. In other configurations, the exhaust can be directed in anysuitable direction to control the draft from the fluid flow.

FIGS. 34A-B illustrate another configuration having two slots 5114. Thevent module 5112 of this interface 5000 has two slots 5114 about 180degrees apart. The slot cover 5115 fits over the vent module 5112,forming the flow path through the slots 5114. This configuration alsoshows a connection port assembly 5106 that is configured to connect withthe slot cover 5115.

FIGS. 35A-B illustrate an embodiment having slots 6114 on the connectionport assembly 6106. The connection port assembly 6106 has twocomponents. A first component with the ball socket 6152 and a secondcomponent with the connection end 6118. When the two components areassembled, a space between the two components can form the slot 6114.The slot 6114 can have the same features as discussed above in otherembodiments.

FIGS. 36A-F illustrate various embodiments of slot designs. FIG. 36Aillustrates radially outward facing slots 7114 at the end of a flaredflow path. As discussed before, the radial direction of the slots canhelp to reduce the draft effects and disturbance to the user and bedpartner. It has been discovered that a slot width of approximately 0.35mm provides good performance in minimizing the noise levels. However, insome embodiments, the slot width can be at least approximately 0.2 mmand/or less than or equal to approximately 0.5 mm.

FIG. 36B illustrates radially outward facing slots 7114 at the end of astraight flow path. FIG. 36C illustrates radially inward facing slots7114 at the end of a bulbous flow path. FIG. 36D illustrates outwardfacing slots 7114 that are tiered. The illustrated embodiment has threetiers of slots 7114. In other embodiments, there can be one, two or morethan three tiers. FIG. 36E illustrates slots 7114 at the end of a flaredflow path which includes an internal curve 7119. The internal curve canencourage the flow direction out through the slots rather than flowinginto a capped surface. The internal curve can provide a smoother fluidflow, which can result in reduced noise levels. FIG. 36F illustratesradially outward facing slots 7114 at the end of a straight flow pathwhich includes an internal curve 7119.

Although certain embodiments, features, and examples have been describedherein, it will be understood by those skilled in the art that manyaspects of the methods and devices illustrated and described in thepresent disclosure may be differently combined and/or modified to formstill further embodiments. For example, any one component of theinterface illustrated and described above can be used alone or withother components without departing from the spirit of the presentinvention. Additionally, it will be recognized that the methodsdescribed herein may be practiced in different sequences, and/or withadditional devices as desired. Such alternative embodiments and/or usesof the methods and devices described above and obvious modifications andequivalents thereof are intended to be included within the scope of thepresent invention. Thus, it is intended that the scope of the presentinvention should not be limited by the particular embodiments describedabove, but should be determined only by a fair reading of the claimsthat follow.

1. A patient interface comprising: a body portion sized and shaped tosurround the nose and/or mouth of a user and adapted to create at leasta substantial seal with the user's face; a frame portion to be held inplace by a headgear assembly that wraps around a user's head, the bodyportion adapted to be secured to the frame portion; a coupling thatpermits the patient interface to be coupled to a gas delivery system; avent that allows the passage of gas from an interior of the body portionto an exterior of the body portion, the vent comprising a plurality ofexit holes arranged in an array; and the frame portion positioned infront of the body portion such that the passage of gas vents through thevent holes and into a plenum chamber created between the body portionand the frame portion.
 2. The patient interface of claim 1, wherein adiameter of each of the plurality of exit holes is between about 0.5 mmand about 1.5 mm.
 3. The patient interface of claim 1, wherein a lengthto diameter ratio of each of the plurality of exit holes is at leastabout
 2. 4. The patient interface of claim 1, wherein a ratio of a pitchdistance between each of the plurality of exit holes to the diameter isat least about
 4. 5. The patient interface of claim 1, wherein an exitradius of each of the plurality of exit holes is at least about 0.5 mmand/or an entry radius of each of the plurality of exit holes is atleast about 0.5 mm. 6-10. (canceled)
 11. The patient interface of claim1, wherein the coupling is a ball-jointed elbow or a swiveling joint.12. The patient interface claim 1, wherein the gas that exits the vententers a diffuser, wherein the diffuser is frustoconical in shape and/orhas an expansion angle of at least about 4 degrees and/or less than orequal to about 8 degrees. 13-16. (canceled)
 17. The patient interface ofclaim 1, wherein the plenum chamber is configured to return the exit gasflow back on itself.
 18. The patient interface of claim 1, wherein theplenum chamber has a cone angle of between about 4 degrees and about 8degrees.
 19. The patient interface of any one of claim 1, wherein theplenum chamber has a length to root diameter ratio of at least about 1.5to
 1. 20-21. (canceled)
 22. The patient interface of claim 1, whereinthe frame portion defines a textured surface facing the vent. 23-26.(canceled)
 27. The patient interface of claim 1, wherein the plenumchamber re-directs the gas flow through an angle of between 45 degreesand about 135 degrees. 28-30. (canceled)
 31. The patient interface ofclaim 1, wherein the plenum chamber is in the shape of an annulus. 32.The patient interface of claim 1, wherein the plenum space also containsa fibrous media, and wherein all of the vented gas exiting the plenumspace into the ambient space passes through the fibrous media. 33-36.(canceled)
 37. The patient interface of claim 1, wherein the plenumchamber is configured to reduce the draft and noise from the vents byenabling the energy present in the exiting fluid flow to dissipate
 38. Apatient interface comprising: a body portion sized and shaped tosurround the nose and/or mouth of a user and adapted to create at leasta substantial seal with the user's face, a coupling that permits thepatient interface to be coupled to a gas delivery system, wherein thecoupling comprises a rotational joint, and a vent that allows thepassage of gas from an interior of the body portion to an exterior ofthe body portion, wherein the vent comprises a plurality of passagesincorporated in the rotational joint of the coupling.
 39. The patientinterface of claim 38, wherein the rotational joint comprises a maleportion and a female portion and the plurality of passages are formed inthe female portion of the coupling.
 40. The patient interface of claim38, wherein the rotational joint comprises a male portion and a femaleportion and the plurality of passages are formed in the male portion ofthe coupling.
 41. The patient interface of claim 38, wherein therotational joint is a ball joint.